Submicron Salt Particle Production in Bubble Bursting

Laboratory experiments of bubble bursting have shown that particle production increases with concentration for aqueous solutions of NaCl (Spiel 1998). Here, experiments with a submicron Na particle counter for three Na salts—NaCl, NaBr, and NaI—show comparable trends. Similarities in behavior are evident when the concentration for each salt is normalized to a threshold concentration (Lessard and Zieminski 1971). The number, size, and mass of particles produced increase with normalized solution concentration, suggesting that the same transition that controls ionic entropy and self-diffusion in aqueous solutions will govern the bubble bursting process. Further insight into the controlling forces is provided by the prediction of the number, size, and mass of particles produced from the Eotvos number, the ratio of buoyant to surface forces of the aqueous solution. The similarities among the parameterizations of particle properties to the Eotvos number for all three Na salts provide a strong indication that, for similar density solutions, particle production is dominated by surface forces, independent of chemical compositions. A complete mechanistic interpretation of particle production is limited by our inability to capture (theoretically or experimentally) both the macroscopic fluid mechanics of film rupture and the microscopic intermolecular interactions of strong ionic solutions. However, the parameterizations to dimensionless quantities of aqueous solutions presented here are sufficient to predict the essential characteristics of particle production. The collapse of the experimental results to common curves for several different salts shows the predictive ability of these parameterizations for other mixtures.

Acknowledgments

The authors are grateful for financial support from the Office of Naval Research (N00014-97-1-0673; N00014-98-0565) and the National Science Foundation (ATM-0408501). Helpful comments from Sandra Troian and Donald Koch are also appreciated.

Notes

^a Lide 2003;

^b Washburn et al. 1928;

^c Weissenborn and Pugh 1996;

^d Abramzon and Gaukhberg 1993;

^e Israelachvili 1992;

^f Lessard and Zieminski 1971;

^g This work (NaI).